The Heartbleed bug may be a devastating flaw still affecting thousands of websites, but efforts to patch any remaining systems are effectively over.

Two months after Heartbleed surfaced in April, more than 300,000 unpatched servers remain vulnerable to Heartbleed. The figure comes from Errata Security's Robert Graham who recently scanned the Internet for a third time to get a count of Heartbleed-vulnerable sites.

A flaw in the online encryption tool OpenSSL, Heartbleed is considered particularly troubling. The bug allows hackers to gather some of the most sensitive data on a website including encryption keys, usernames and passwords, and user data.

Currently, there are about 309,197 systems still vulnerable to Heartbleed, which is a slight drop from the 318,239 Graham discovered in early May. The slow drop indicates that Heartbleed patching has more or less ended.

Graham says he expects to see a decrease in Heartbleed vulnerabilities as older hardware gets swapped out for newer servers with upgraded software. Nevertheless, says Graham, "a decade from now, I still expect to find thousands of systems, including critical ones, still vulnerable."

To come up with his count, Graham scanned servers over port 443, the most common interface server's use for SSL connections.

The one annoyance about Graham's count is that he's reluctant to name any of the sites that showed up on his Heartbleed hit list. Publicizing a list of sites or contacting the sites directly would be more trouble than it's worth, as Graham notes in the comments of his blog post. Publicizing a list would create a road map for hackers and, given the current legal and political climate towards security researchers, create a real headache for Graham himself. Nevertheless, as a user it would be nice to know if any major websites were still on that list.

Following this most recent scan, Graham says he plans on running Heartbleed vulnerability scans in July, October, and then once a year after that.

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